1. Field of the Invention
This invention relates generally to a closed loop vapor cycle refrigeration system, and more particularly to a refrigeration system which utilizes energy of the condensate liquid refrigerant to elevate the pressure in the suction line.
2. Description of the Related Art
Most modern refrigeration systems utilize what is known as the vapor compression refrigeration cycle. The efficiency of such refrigeration systems depend upon the losses which occur in such systems and the type of the refrigerant used. Thermo-mechanical expansion valves are typically used to control the flow of the liquid refrigerant to the evaporator of the refrigeration system. The liquid refrigerant passes to the evaporator through the expansion valve, wherein the liquid refrigerant expands. The expansion process at the expansion valve releases thermal energy stored in the liquid refrigerant as kinetic energy of gas molecules. This expansion process is inefficient.
To improve the efficiency of the refrigeration system, temperature of the liquid refrigerant is often lowered so as to lower the thermal energy of the liquid refrigerant before it passes to the expansion valve, thereby decreasing the amount of energy which will have to be removed by the latent evaporation process in the evaporator. A common method employed to lower the temperature of the liquid refrigerant before supplying it to the expansion valve is to store the liquid refrigerant in a receiver or reservoir.
The reservoir, which is at the high pressure side of the refrigeration system, also acts as a liquid-gas separator. The liquid refrigerant from the reservoir is passed to the expansion valve, but the gas in the reservoir remains unutilized. The gas from the reservoir, however, can be removed from the reservoir to lower the pressure in the reservoir. Lowering the pressure in the reservoir further lowers the temperature of the liquid refrigerant in the reservoir before it enters the evaporator, which is not generally done. The gas removed from the reservoir may be used to perform some useful function in the refrigeration system to further improve the refrigeration system efficiency, but is also not generally done.
The present invention provides a refrigeration system wherein energy from the high pressure side of the refrigeration system is used to elevate the pressure in the suction line above the evaporator pressure to improve the overall efficiency of the refrigeration system.